Low-density nonwoven fabric and production method and installation therefor and uses

ABSTRACT

The invention concerns an installation for nonwoven production, characterized in that it comprises a spunbonded web plant whereof the die is inclined at an angle of 10 to 60° and preferably of 20 to 50° relative to the displacement direction of a conveyor and preferably two spunbonded web plants whereof the dies have opposite inclinations, said conveyor whereon filaments are deposited from the die(s) in the form of a web, a station for compressing the thus formed web into a web compressed perpendicular to its plane, optionally a station for calendering the compressed web, followed by a station for consolidating by pressurized water jet spray the compressed and optionally calendered web with a jet spraying machine comprising a metal fabric whereof the wires have a diameter between 0.10 and 0.35 mm and which has more than 40 wires per cm and preferably 10 to 30 wires per cm both in warp direction and in weft direction or with a water jet spraying machine including a sleeve with perforations of 50 to 600 microns and having 20 to 200 perforations per cm 2 .

This application is a division of prior application Ser. No. 10/529,843,filed Mar. 31, 2005.

The present invention relates to nonwoven fabrics and to theirproduction methods and installations and to their applications.

To manufacture hygiene products, such as diapers, adult incontinencepads, sanitary towels, etc., it is desirable to manufacture them from amaterial having as low a density as possible and a tensile strength asisotropic as possible.

For this, the invention provides a method of producing a nonwoven inwhich filaments coming from a spunbond unit with a die are deposited asa web having a longitudinal direction onto a conveyor, the web iscompressed, perpendicular to the plane of the web, into a compressed weband then the compressed web is subjected to a consolidation operation byblasting it with water jets having a diameter of 50 to 250 microns at apressure of 50 to 500 bar. According to the invention, the web isdeposited onto the conveyor using at least one spunbond unit, the die ofwhich is inclined at an angle of from 10 to 60° and preferably from 20to 50° relative to the longitudinal direction and preferably using atleast two spunbond units, the dies of which are inclined in oppositedirections, and the water jets are blasted, with interposition of theweb, either onto a metal fabric the threads of which have a diameter ofbetween 0.10 mm and 0.35 mm and which have at most 40 threads percentimeter in the warp direction and 40 threads per centimeter in theweft direction, or onto a microperforated sleeve, the dimensions of theperforations of which are between 50 and 600 microns and preferablybetween 150 and 500 microns, and which has a number of perforations percm² of between 50 and 200.

Preferably, the threads have a diameter of between 0.18 and 0.30 mm andthe number of threads per centimeter in the fabric both in the warpdirection and in the weft direction is from 15 to 30.

With these conditions, what is obtained by the method according to theinvention is a nonwoven fabric made from filaments, having a density ofless than 0.10 g/cm³ and especially between 0.09 g/cm³ and 0.03 g/cm³and better still between 0.07 and 0.03 g/cm³, and a ratio of theultimate tensile strength in the machine direction to the ultimatetensile strength in the cross direction of less than 1.5, and even lessthan 1.3 or indeed less than 1.1. A nonwoven fabric according to theinvention thus combines isotropy of properties with a very low density,which makes this nonwoven fabric incompatible for manufacturing diapers,either as covering layer in contact with the baby's skin or as an outertextile lining to give a textile appearance. The nonwovens according tothe invention may also be used as covering layer for feminine hygieneproducts, as covering sheets for plants under cultivation in theagricultural field, as filter media for filtering air or gases orliquids, as coating substrates and as wiping products. The nonwovenaccording to the invention has a better rate of acquisition and a higherrate of spread, which makes it particularly useful for diapers.Furthermore, a liquid diffusion ring on the nonwoven according to theinvention is substantially circular, which further increases the usefularea for acquisition and absorption of the liquid. In filtration, alarger instantaneous retentivity is found, to the point that only asingle layer of the nonwoven according to the invention is equivalent tofilter media consisting of four layers according to the prior art.Furthermore, the lifetime of the filter is extended.

For the covering layer of a diaper, it is preferred that the titer bebetween 1 and 3 dtex and that the weight be between 12 and 20 g/m². Forthe spread layer of a diaper or sanitary napkin, it is preferred thatthe titer be between 3 and 8 dtex and especially between 3 and 7, andthat the weight be between 30 and 50 g/m² and 7 dtex, the spread layerthus acting as an acquisition layer. For the layers to ensure sealingalong the edges, along the leg cuffs, a titer of between 1 and 3 dtexand a weight of 15 to 30 g/m² are preferred. In the agricultural use assheeting for covering plants, a titer of between 2 and 6 dtex andespecially between 3 and 4 dtex and a weight of 15 to 30 g/m² arepreferred. The same will apply to sheeting for forcing in agriculture.In filtration, it is possible to have very different dtex titers rangingfrom 1 to 8 dtex, especially with a preference for titers of between 4and 6 dtex, and a weight of between 30 g/m² and 150 g/m^(2.) Forimpregnation and coating substrates, such as those used for example inthe building and civil engineering fields, and in the manufacture ofartificial and synthetic leather, titers of between 1 and 8 dtex, with apreference for titers of between 2 and 6 dtex, are found.

The invention is suitable for uncrimped filaments, which considerablysimplifies the method of production. However, optionally the filamentsmay also be crimped, although this is not preferred as it complicatesthe manufacture.

The invention is particularly preferred for nonwovens with a weight ofbetween 12 and 50 g/m².

These remarkable properties may be explained by the fact that, by havingthe spunbond unit inclined, a web is obtained whose filaments are betterintertwined, the web thus being more able to withstand, without creatingholes, the pressure of the water jets, the filaments of the web beingbetter entangled by the water-jet bonding.

Preferably, the metal fabric is made of steel or bronze and has athickness of between 0.40 and 0.75 mm. It is most particularly preferredfor the metal fabric to have a plain weave, a twill weave or a satinweave.

The first step of the method according to the invention consists indepositing filaments onto a conveyor as a web. The filaments mayespecially be made of a polyolefin, a polyester, a polyamide, apolyvinyl alcohol, a metallocene, a polylactic acid or any othersuitable plastic. The filaments preferably have a titer of between 0.9and 10 dtex.

They are output from a die at the top of the spunbond unit and thendescend vertically down to the conveyor, passing through a device thatcools them and draws or attenuates them in a conventional manner exceptthat, according to the invention, it is preferred to use two spunbondunits whose dies are inclined, preferably in opposite directions, at anangle of 10 to 60° and preferably 20 to 50° relative to the longitudinaldirection of the web, which is the direction in which the conveyor movesand is also called the machine direction. The angles of inclination ofthe two dies may be different, one of them possibly also beingperpendicular to the longitudinal direction of the web.

The second step of the method consists in compressing the web into acompressed web while it is on the conveyor. This compression is carriedout by standard mechanical means, especially by making the web passthrough the nip between two rolls or by compressing it between theconveyor and a roll.

The third step of the method according to the invention consists inconsolidating the compressed web by blasting it with water jets having adiameter of 50 to 250 microns under a pressure of 50 to 500 bar. Thisinvolves bonding the web by water-jet entanglement, which is aconventional process, except that care is taken to make the water jetspass through a metal fabric, the threads of which have a prescribeddiameter, the number of threads of which per centimeter in the fabricbeing prescribed in the warp direction and in the weft direction, orthrough a microperforated sleeve, as described above.

The diameter of the jets is preferably between 80 microns and 200microns. In general, the jets are arranged in one row or in severalrows, the arrangement in one row being preferred. The distance betweentwo jets of any one row is in general between 0.3 mm and 1.4 mm, andpreferably between 0.4 mm and 0.6 mm. The consolidation treatment mayalso be carried out on several successive drums, each equipped with oneor more water-jet injectors, especially when the production rate is veryhigh, for example being 800 m per minute. At these speeds, the use oftroughs, attached to the injectors, for recovering the rebounding waterjets is particularly useful. In general, these speeds are between 20m/min and 1000 m/min. In particular, it is possible to combine a fabricdrum with microperforated sleeve drum roll.

The metal fabric, termed the outer fabric, may be mounted directly on arotating support drum, but it may also be mounted on a coarser metalfabric, called inner fabric, consisting of threads having a diameter ofat least 0.5 mm, which fabric serves as a draining fabric. The innermetal fabric is thus inserted between the rotating drum and the outermetal fabric, preferably being in contact with them. The drum consistsof a fixed hollow cylinder with slots provided around periphery, whichslots face the injectors and are intended to extract the water. Thefixed drum has, around its periphery, a rotating drum consisting of arigid permeable support. The drum has a diameter of between 300 mm and1000 mm and preferably between 500 mm and 900 mm. The water extractionslots opposite the injectors preferably have a width of between 5 and 50mm and preferably between 15 and 40 mm. The nonwoven fabric made offilaments obtained by the method according to the invention has a highsoftness. However, if this softness may be dispensed with, it ispossible for the other two desired properties, namely a low density anda machine direction strength/cross direction strength ratio close tounity, to be further improved by choosing, as drum, a metal sleeveperforated with holes of between 50 and 600 microns and preferablybetween 150 and 500 microns in diameter, there being from 20 to 200holes per cm² and preferably 70 to 150 holes/cm².

If it is also desired to increase the strength of the nonwoven fabricobtained, the compressed web has to undergo a calendering operationbefore being consolidated. This calendering operation is carried out ina standard calender at a temperature of 100 to 250° C. and preferably130 to 170° C., depending on the nature of the constituent polymer ofthe filaments (for example for polypropylene webs, this is preferablycarried out between 130 and 180° C.), with a web area that has melted of5 to 40% and preferably 10 to 30% of the total area, it being possiblefor the points of melting to be circular, oval, rectangular,diamond-shaped or the like.

The calendering may consist in passing the web of thermoplasticfilaments between heated rolls. To carry out the invention, it ispreferred to use a calender consisting of a smooth roll and an etchedroll. The pressure and temperature that are applied by the calendercause spot melting of the web of continuous filaments.

The etching may consist of spots of circular, oval, square, rectangularor even diamond shape. The spots of melting on the surface of the webrepresent from 2 to 40%, and preferably from 10 to 30%, of the area.

It is also possible to use two etched rolls of the male/female type thatundergo synchronized rotation and mutual imbrication. It is alsopossible to use two smooth rolls.

The calendering is carried out at pressures of between 50 N/mm and 150N/mm.

The calendering speeds may reach several hundred meters per minute andespecially 100 to 800 m/min.

The strength index, expressed as newtons per 50 mm per gram of nonwovenper m² is particularly good if the calendering operation is incorporatedinto the method according to the invention. It may reach 2.8, i.e. 1.5in the machine direction and 1.3 in the cross direction, while theweight of the nonwoven fabric is between 12 and 150 g/m , preferably 12to 100 g/m² and better still 12 to 40 g/m². Preferably a strength indexof at least 3.5 and better still at least 4.5, or even at least 5.5, maybe achieved.

By way of comparison, a conventional 20 g/m² nonwoven composed of 100%1.7 dtex polypropylene, which has been carded and calendered, is soldwith a thickness of 0.16 mm, a machine direction tensile strength of 40N/50 mm and a cross direction tensile strength of 9 N/50 mm, i.e. amachine direction strength/cross direction strength ratio of 4.44. Owingto their poor mechanical properties, it is not possible to reduce theweight per square meter of these carded and then calendered nonwovens.With nonwovens formed from continuous filaments according to theinvention, it is possible to obtain nonwovens that are thicker,stronger, more isotropic and with a lower weight per square meter.

After the consolidation device, for entanglement by means of pressurizedwater jets, the residual water present in the nonwoven is extracted bysuction devices connected to vacuum generators, and then the nonwoven isdried, for example in a through-air oven, or with infrared panels orusing microwaves. The final nonwoven obtained has a water content ofless than 5% by weight.

Before or after drying, a surfactant may be applied to the nonwoven.

The invention also relates to a nonwoven production installationcomprising at least one spunbond unit whose die is inclined at an angleof 10 to 60°, and preferably 20 to 50°, relative to the longitudinaldirection, and preferably at least two spunbond units whose dies areinclined, in opposite directions, which deposit filaments onto aconveyor as a web, a device for compressing the web perpendicular to theplane of the web so as to obtain a compressed web, optionally a calenderthat calenders the compressed web, and then a water-jet device forconsolidating the compressed and optionally calendered web by blastingit with water jets having a diameter of 50 to 250 microns and under apressure of 50 to 500 bar, the installation including a water-jetblasting machine having a metal fabric or a perforated sleeve, asindicated above.

Laboratory tests for measuring thickness, density, strength in themachine direction and strength in the cross direction were carried outaccording to the ERT standards of the EDANA (European Disposables AndNonwovens Association), namely:

a) Thickness:

The specimen is conditioned for 24 hours and the test is carried out at23° C. and at a relative humidity of 50%. The thickness of the nonwovenis measured by measuring the distance between a reference plate, onwhich the nonwoven rests, and a parallel press plate which applies aprecise pressure to the surface subjected to the test. The apparatusconsists of two circular horizontal plates fixed to a frame. The upperplate moves vertically. It has an area of about 2500 mm². The referenceplate has a flat surface with a diameter of at least 50 mm more thanthat of the upper plate.

The test piece has dimensions of 180×80 mm±5 mm for the width and thelength. A measurement device is provided that measures the distancebetween the plates when these are brought close together to the point ofapplying a pressure of 0.02 kPa.

b) Strength and Elongation in the Machine Direction and in the CrossDirection:

A specimen is conditioned for 24 hours and the test is carried out at23° C. and at a relative humidity of 50%. A tensile testing machine isused for the test, comprising a set of fixed jaws and a set of movingjaws, which move at a constant speed. The jaws of the tensile testingmachine have a useful width of 50 mm. The tensile testing machine isequipped with a recorder that allows the curve of the tensile force as afunction of the elongation to be plotted. Five specimens 50 mm±0.5 mm inwidth and 250 mm in length are cut, in the machine direction and in thecross direction, from the nonwoven. The specimens are tested one by one,at a constant pull speed of 100 mm per minute and with an initialdistance between the jaws of 200 mm. The tensile testing machine recordsthe curve of the tensile force in newtons as a function of theelongation, the maximum point of which is determined.

c) Weight Per Square Meter:

A specimen in conditioned for 24 hours and the test is carried out at23° C. and at a relative humidity of 50%. At least three specimens withan area of at least 50 000 mm² are cut with a cutting device called apress-cutter. Each specimen is weighed on a laboratory balance having aprecision of 0.1% of the mass of the specimens weighed.

d) Density:

The density is calculated from the measured thickness and from the massper square meter:d=g/(t×1000)in which d=density in grams per cubic centimeter

-   -   g=mass per square meter of the nonwoven;    -   t=thickness (expressed in mm) of the nonwoven tested.

In the appended drawing given solely by way of example:

FIG. 1 is a partial schematic plan view of an installation according tothe invention; and

FIG. 2 is a complete plan view.

The installation shown in FIG. 1 comprises two spunbond units 1, 2having a die 3, 4, respectively, which deposit, on the upper run 5 of anendless belt 5 of a conveyor 6 passing over return, tensioning andguiding rollers 7, a web of continuous filaments which then pass fromthe left to the right in FIG. 1 through compacting rolls 8 and 9 beforepassing through a calender 10 consisting of two rolls and then, via aconveyor 11, onto a water-jet blasting machine. The machine comprises afixed inner drum 12, onto which is slipped either a hollow cylinder 13made of metal fabric, the threads of which have a diameter of 0.25 mmwith 22 threads per centimeter in the warp direction and 22 threads percentimeter in the weft direction, or a microperforated sleeve, thedimensions of the perforations of which are 200 microns and the numberof perforations per cm² being 100. The metal fabric has a thickness of0.50 mm and a satin weave. The web passes over the metal fabric 13 andreceives water jets 100 microns in diameter at a pressure of 300 bar viainjectors 14.

FIG. 2 shows that the longitudinal axis Y, Y′ of the die 3 and thelongitudinal axis Z, Z′ of the die 4 are inclined at an angle a and anangle b, respectively, to the axis X, X′, which corresponds to themachine direction but in the opposite sense. FIG. 2 shows, after thewater jet blasting machine, that a dewatering conveyor 15, a drying oven16 and a winding device 17 are provided.

EXAMPLES

All the examples 1 to 10 were produced with a 20 g/m² spunbond nonwovenproduced on a PERFOBOND installation sold by Rieter Perfojet, composedof 1.7 dtex polypropylene filaments. This nonwoven had the feature ofhaving a machine direction strength/cross direction strength ratio ofless than 1.5, this being particularly advantageous in manyapplications. The nonwoven had a thickness of 0.15 mm, a machinedirection strength of 39.8 N/50 mm and a cross direction strength of32.1 N/50 mm. It had a density of 0.133 g/cm³.

After hot calendering, the nonwoven was treated with water jets on aJETLACE machine sold by Rieter Perfoject, which was composed of a hollowcylindrical drum at the periphery of which various jackets or cylindersrotated. It is on the surface of these rotating cylinders that thefilaments were treated with water jets. A water-jet injector wasinstalled on the periphery of the drum and the jets that it deliverswere directed toward the cylinder.

The water injection system delivered jets 120 microns in diameter, thejets being spaced apart from one another by 0.6 mm. A vacuum of −800mbar was applied to the inside of the hollow cylindrical drum by avacuum generator.

All the tests were carried out at a linear speed of 200 m/min. All thespecimens were predried on a conveyor provided with suction slots andthen dried in a through-air oven at a temperature of 100° C. beforebeing wound up.

Example 1: (Comparative Example)

The drum was equipped with a cylinder C1 consisting of a perforatedstainless steel sheet covered with a bronze fabric made up from threads0.63 mm in diameter in the warp direction and threads 0.51 mm indiameter in the weft direction. It comprised 9.5 warp threads per cm and8.5 weft threads per cm.

The injector was supplied with a pressure of 100 bar. The thickness ofthe nonwoven increased, but its surface was perforated with many holesfrom 0.4 to 0.5 mm² in area. Its handle is softer than that of theuntreated nonwoven, but the perforations make it unusable.

Example 2

The drum was fitted with a cylinder C2 consisting of a perforatedstainless steel sheet covered with a metal fabric made of stainlesssteel consisting of threads 0.11 mm in diameter in the weft directionand threads 0.14 mm in diameter in the warp direction. It comprised 39warp threads per cm and 36 weft threads per cm.

The strength index I=(39.8+32.1)/20 was 3.35, whereas, withouttreatment, it was 3.59.

The injector was supplied at a pressure of 170 bar. The nonwovenincreased in thickness and its handle was softer than the initialnonwoven. It was free of defects and perforations, with I=3.3.

Example 3

Example 2 was repeated with a pressure of 230 bar. The nonwovenincreased in thickness and its handle was softer than the initialnonwoven (i.e. that of Example 1) and softer than that of Example 2. Itwas free of defects and perforations, with I=3.16.

Example 4

Example 3 was repeated with a pressure of 300 bar. The nonwovenincreased in thickness and its handle was softer than the initialnonwoven and softer than that of Example 3. It was free of defects andperforations, with I=2.67.

Example 5: (Preferred Example)

The drum was fitted with a cylinder C3 consisting of a perforatedstainless steel sheet covered with a bronze fabric made up of 0.22 mmdiameter threads in the warp direction and 0.23 mm diameter threads inthe weft direction. It comprised 25 warp threads per cm and 20 weftthreads per cm.

The injector was supplied at a pressure of 170 bar. The nonwovenincreased in thickness and its handle was softer than the nonwoven ofExample 1 and softer than the nonwovens of Examples 2, 3 and 4. It wasfree of defects and perforations, with I=3.42.

Example 6: (Preferred Example)

Example 5 was repeated with a pressure of 230 bar. The nonwovenincreased in thickness and its handle was softer than the nonwoven ofExample 1 and that of Example 5. It was free of defects andperforations, with I=3.39.

Example 7: (Preferred Example)

Example 6 was repeated with a pressure of 300 bar. The nonwovenincreased in thickness and its handle was softer than the nonwoven ofExample 1 and that of Example 5. It was free of defects andperforations, with I=3.

Example 8

The drum was fitted with a cylinder C4 consisting of a perforated rigidcylindrical sheet covered with a nickel sleeve 0.35 mm in thickness andperforated with holes 250 to 350 microns in diameter, comprising 100holes per cm², the holes being randomly distributed.

The injector was supplied at a pressure of 170 bar. The nonwovenincreased in thickness and its handle was softer than the initialnonwoven. It was free of defects and perforations, with I=3.55.

Example 9

Example 8 was repeated with a pressure of 230 bar. The nonwovenincreased in thickness and its handle was softer than the nonwoven ofExample 1 and that of Example 8. It was free of defects andperforations, with I=3.51.

Example 10

Example 8 was repeated with a pressure of 300 bar. The nonwovenincreased in thickness and its handle was softer than the initialnonwoven and that of Example 9 (however, it was not so soft as thenonwoven of Example 7). It was free of defects and perforations, withI=3.21.

The results of Examples 1 to 10 are set out in the table below:

This table shows that thickness increases from about 50% to more than100% are obtained, while still having densities that are very much lessthan those of the nonwoven of Example 1 and for machine directionstrength/cross direction strength ratios that are substantiallyequivalent.

Example 11

A 140 g/m² nonwoven according to the invention, formed from 1.5 dtexpolypropylene filaments, was subjected to a filtration test using sodiumchloride particles 0.26 microns in diameter suspended in air. Theapparatus was of the TSI CERTITEST 8130 type and the air flow ratethrough the specimen was 103 l/min. A 77% efficiency and a head loss of420×10⁻⁵ bar were obtained.

Using the same apparatus and under the same conditions, a 170 g/m²product normally used as filtration medium, consisting of four layers ofmeltblown, spunbond nonwoven, consisting of polypropylene fiber andpolypropylene calendered fiber, was tested. The efficiency was 74% andthe head loss was 540×10⁻⁵ bar.

The nonwoven according to the invention had a better efficiency and alower head loss, while still having a lower weight per unit area. Thenonwoven according to the invention that was used had a machinedirection strength of 300 N/50 mm and a cross direction strength of 300N/50 mm, i.e. a ratio between the two of 1.1. Its thickness was 1.9 mmand its density was 0.074 g/cm³, with I=4.5. MD CD (machine (crossdirection) direction) Loss of Thickness strength strength strength,Thickness increase Density (N/50 (N/50 MD + CD Example (mm) (%) (g/cm³)mm) mm) (%) Handle No 0.15 — 0.133 39.8 32.1 — − treatment 1 0.23 53.30.087 37.0 30.1 4.8 − 2 0.22 46.7 0.091 36.3 29.7 5.9 + 3 0.26 73.30.077 35.1 28.2 8.6 ++ 4 0.29 93.3 0.069 29.7 23.8 18.4 +++ 5 0.24 60.00.083 38.0 30.3 3.6 +++ 6 0.28 86.7 0.071 37.5 30.4 4.0 ++++ 7 0.32113.3 0.063 33.2 26.8 11.9 +++++ 8 0.26 73.3 0.077 39.1 32.0 0.8 + 90.29 93.3 0.069 39.3 30.8 2.8 ++ 10 0.32 113.3 0.063 35.0 29.2 7.7 ++

handle was tested by a panel. The best handle is denoted by +++++, theleast good.

1-9. (canceled)
 10. A method of producing a nonwoven, in which filamentsare deposited as a web in a plane on a conveyor having a longitudinaldirection, the web is compressed, perpendicular to the plane of the web,into a compressed web and then the compressed web is subjected to aconsolidation operation by blasting it with water jets having a diameterof 50 to 250 microns at a pressure of 50 to 500 bar to form thenonwoven, including the steps of: depositing the filaments onto theconveyor using at least one spunbond unit including a die which isinclined relative to the longitudinal direction at an angle of 10 to60°; and blasting the web with the water jets with either: a)interposition of the web, onto a metal fabric, having warp and weftthreads of a diameter between 0.10 mm and 0.35 mm, the warp and weftthreads each numbering up to 40 threads per cm, or b) interposition ofthe web, onto a microperforated sleeve, the dimensions of theperforations being between 50 and 600 microns and the number ofperforations being between 50 and 200 per cm².
 11. The method of claim10, wherein said die is inclined at an angle of from about 20° to about50°, said threads have a diameter of diameter between 0.18 mm and 0.30mm, the warp and weft threads each number between 15 to 30 threads percm, the dimensions of the perforations are between 150 and 500 microns,and the number of perforations is between 50 and 200 per cm².
 12. Themethod as claim in claim 10, wherein the metal fabric has a plain, twillor satin weave and a thickness of between 0.40 mm and 0.75 mm.
 13. Themethod of claim 10, further including a second spunbond unit having asecond die depositing filaments onto the conveyor, and the second die isinclined relative to the longitudinal direction at an angle of fromabout 10° to about 60°.
 14. The method of claim 13, wherein said diesare inclined in opposite directions.
 15. The method of claim 13, whereineach of said dies is inclined at an angle of from about 20° to about50°, said threads have a diameter of diameter between 0.18 mm and 0.30mm, the warp and weft threads each number between 15 to 30 threads percm, the dimensions of the perforations are between 150 and 500 microns,and the number of perforations is between 50 and 200 per cm².
 16. Amethod producing a nonwoven having an indefinite length and a widthcomprising the steps of extruding filaments from a die, depositing theextruded filaments onto a conveyor to form the nonwoven in a planeextending along said conveyor, said nonwoven length extending along theconveyor length and said nonwoven width extending across the conveyorwidth, disposing the die at an inclined angle relative to the plane ofthe nonwoven to thereby increase the number of die deposited filamentsacross the width of the nonwoven as compared with an identically formednonwoven except that the die is not disposed at said inclined anglerelative to the plane of the nonwoven.
 17. The method of claim 16,wherein said inclined angle is from about 10° to about 60°.
 18. Themethod of claim 16, further including a second die, extruding filamentsfrom said second die and depositing the extruded filaments onto theconveyor to form the nonwoven, said second die also being inclinedrelative to the plane of the nonwoven at an angle of from about 10° toabout 60°.
 19. The method of claim 18, wherein said first mentioned dieand said second die are inclined in opposite directions.
 20. The methodof claim 16, further including the steps of compressing the nonwoven,and consolidating the compressed nonwoven by impinging water jets ontothe compressed web.
 21. The method of claim 20, wherein the step ofimpinging water jets onto the compressed nonwoven includes either: a)positioning the compressed nonwoven, onto a metal fabric, having warpand weft threads of a diameter between 0.10 mm and 0.35 mm, the warp andweft threads each numbering up to 40 threads per cm, or b) positioningthe compressed nonwoven, onto a microperforated sleeve, the dimensionsof the perforations being between 50 and 600 microns and the number ofperforations being between 50 and 200 per cm².
 22. The method of claim21, wherein said inclined angle is from about 20° to about 50°, saidthreads have a diameter of diameter between 0.18 mm and 0.30 mm, thewarp and weft threads each number between 15 to 30 threads per cm, thedimensions of the perforations are between 150 and 500 microns, and thenumber of perforations is between 50 and 200 per cm².
 23. The method ofclaim 21, further including a second die, extruding filaments from saidsecond die and depositing the extruded filaments onto the conveyor toform the nonwoven, said second die also being inclined relative to theplane of the nonwoven at an angle of from about 10° to about 60°. 24.The method of claim 23, wherein each of said inclined angles is fromabout 20° to about 50°
 25. The method of claim 24, wherein said firstmentioned die and said second die are inclined in opposite directions.26. A nonwoven production installation comprising a spunbond unit havinga die inclined at an angle of from about 10° to about 60° relative tothe direction of movement of a conveyor and arranged to depositfilaments across the width of the conveyor to form a web, a compressionstation for compressing the web thus formed perpendicular to its planeinto a compressed web, and a consolidation station for blastingpressurized water jets onto the compressed web using a water-jetblasting machine to form the nonwoven, the water-jet blasting machineincluding either (a) a metal fabric, the threads of which have adiameter of between 0.10 mm and 0.35 mm, there being at most 40 threadsper cm in each of the warp direction and the weft direction, or (b) asleeve having 50 to 600 micron perforations, there being 20 to 200perforations per cm².
 27. The installation of claim 26, wherein saidangle is from about 20° to about 50° and there are 15 to 30 threads percm in each of the warp direction and the weft direction.
 28. Theinstallation of claim 26, wherein said inclined angle is from about 20°to about 50°, said threads have a diameter of diameter between 0.18 mmand 0.30 mm, the warp and weft threads each number between 15 to 30threads per cm, the dimensions of the perforations are between 150 and500 microns, and the number of perforations is between 50 and 200 percm².
 29. The installation of claim 26, further including a secondspunbond unit having a second die inclined at an angle of from about 10°to about 60° relative to the direction of movement of a conveyor. 30.The method of claim 29, wherein each of said dies is inclined at anangle of from about 20° to about 50°, said threads have a diameter ofdiameter between 0.18 mm and 0.30 mm, the warp and weft threads eachnumber between 15 to 30 threads per cm, the dimensions of theperforations are between 150 and 500 microns, and the number ofperforations is between 50 and 200 per cm².
 31. The installation ofclaim 26, wherein said compression station comprises a calendar forcompressing the nonwoven.
 32. The installation of claim 26, wherebyinclination of the die increases the number of die deposited filamentsacross the width of the nonwoven as compared with an identically formednonwoven except that the die is not inclined relative to the directionof movement of the conveyor.
 33. A nonwoven production installation forproducing a nonwoven having an indefinite length and a width comprisinga die for extruding filaments onto a conveyor to form the nonwoven in aplane extending along said conveyor, said nonwoven length extendingalong the conveyor length and said nonwoven width extending across theconveyor width, said die being disposed at an inclined angle relative tothe plane of the nonwoven to increase the number of die depositedfilaments across the width of the nonwoven as compared with anidentically formed nonwoven except that the die is not disposed at saidinclined angle relative to the plane of the nonwoven.
 34. Theinstallation of claim 33, wherein said inclined angle is from about 10°to about 60°.
 35. The installation of claim 33, further including asecond die for extruding filaments onto the conveyor to form thenonwoven, said second die also being disposed at an inclined angle offrom about 10° to about 60° relative to the plane of the nonwoven. 36.The installation of claim 35, wherein said first mentioned die and saidsecond die are inclined in opposite directions.
 37. The installation ofclaim 33, further including a compressing station for compressing thenonwoven in a direction perpendicular to the plane of the nonwoven, anda consolidation station for consolidating the compressed nonwovenincluding means for impinging water-jets jets onto the compressednonwoven.
 38. The installation of claim 37, wherein the means forimpinging water-jets onto the compressed nonwoven include either: a) ametal fabric onto which the compressed web is positioned, the metalfabric having warp and weft threads of a diameter between 0.10 mm and0.35 mm, the warp and weft threads each numbering up to 40 threads percm, or b) a microperforated sleeve onto which the compressed web ispositioned, the dimensions of the perforations being between 50 and 600microns and the number of perforations being between 50 and 200 per cm².39. The installation of claim 38, wherein said inclined angle is fromabout 20° to about 50°, said threads have a diameter of diameter between0.18 mm and 0.30 mm, the warp and weft threads each number between 15 to30 threads per cm, the dimensions of the perforations are between 150and 500 microns, and the number of perforations is between 50 and 200per cm².
 40. The installation of claim 38, further including a seconddie for extruding filaments onto the conveyor to form the nonwoven, saidsecond die also being disposed at an inclined angle of from about 10° toabout 60° relative to the plane of the nonwoven.
 41. The installation ofclaim 40, wherein each of said inclined angles is from about 20° toabout 50°
 42. The installation of claim 41, wherein said first mentioneddie and said second die are inclined in opposite directions.